442 MR. C. DARAVTX OX SPEOirXC DirrEKEXCES TX PRIMULA 



garden ; and if Prof. Henslow took by mistake seeds from one of 

 these plants, especially if it had been accidentally crossed by a 

 Primrose, the result would be quite intelligible. Another case is 

 still more difficult to understand: Dr. Herbert* raised, from seed 

 of a highly cultivated red Cowslip, Cowslips, Oxlips of various 

 kindsj and a Primrose. This case, if accurately recorded, is expli- 

 cable only on the improbable assumption that the r^^ Cowslip was 

 not of pure parentage. With plants of many kinds, when crossed, 

 one species or variety is sometimes strongly prepotent over the 

 other : and instances are known f of one variety crossed by an- 

 other producing offspring which in certain characters, as in 

 colour, hairiness, &c., have proved identical with the pollen-bearing 

 parent, and quite dissimilar to the mother plant; but I do not 

 know of any good instance of the offspring of a cross perfectly 

 resembling, in a number of important characters, the father 

 alone. Hence w^e cannot admit that a pure Cowslip crossed by a 

 Primrose would ever produce a Primrose in appearance pure. 

 Although the facts given by Dr. Herbert and Prof. Henslow are 

 difficult to explain, yet until it can be shown that a Cowslip or a 

 Primrose, carefully protected from insects, will occasionally give 

 birth to at least Oxlips, the cases hitherto recorded have little 

 weight in leading us to admit that the Cowslip and Primrose are 

 varieties of one and the same species, 



Negative evidence is of little value ; but the following facts may 

 be worth giving: — Some Cowslips which had been transplanted 

 from the fields into a shrubbery were again transplanted into 

 highly manured land. In the following year they were protected 

 from insects, artificially fertilized, and the seed thus procured was 

 sown in a hotbed. The young plants were afterwards planted 

 out, some in very rich soil, some in stiff poor clay, some in old 

 peat, and some in pots in the greenhouse ; so that these plants, 

 765 in number, as well as their parents, were subjected to diversi- 

 fied and unnatural treatQient ; but not one of them presented the 

 least variation except in size — those in the peat growing to almost 

 gigantic dimensions, and those in the clay being much dwarfed. 



I do not, of course, doubt that Cowslips exposed during several 

 successive generations to changed conditions would vary, and that 

 this would occasionally take place in a state of nature. Moreover, 

 from the law of analogical variation, the varieties of any one 



* Transact. Hort. Soc. iv. p. 19. 



On the Variation of An 



un 



